Resin composition for heat dissipation and heat dissipating substrate manufactured by using the same

ABSTRACT

Disclosed herein are a resin composition for heat dissipation, including: an insulating material; a first filler added to the insulating material and having a plate shaped carbon material; and a second filler added to the insulating material, and having a carbon material having a higher aspect ratio than the first filler.

CROSS REFERENCE(S) TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. Section 119 of Korean Patent Application Serial No. 10-2012-0150948, entitled “Resin Composition for Heat Dissipation and Heat Dissipating Substrate Manufactured by Using The Same” filed on Dec. 21, 2012, which is hereby incorporated by reference in its entirety into this application.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a resin composition for heat dissipation and a heat dissipating substrate manufactured by using the same, and more particularly, to a resin composition for heat dissipation and a heat dissipating substrate manufactured by using the same, capable of improving heat dissipation efficiency.

2. Description of the Related Art

As electronic products become recently multifunctional and highly integrated, there has been also an increasing demand for a high-efficiency heat dissipation technology for effectively dissipating the heat generated from the electronic components. There are a technology of providing a heat sink, a technology of providing a flow path through which a cooling water flows, such as, a heat pipe or a heat channel, a technology of providing a via having high heat conductivity as a heat dissipation route, and the like, in heat dissipation technologies for general electronic chip components. However, these technologies require a relatively large installation area, and thus have difficulty in a trend of miniaturizing electronic components. Therefore, technologies of using a resin composition containing a heat-conductive filler as a heat dissipating material have been developed.

However, the heat-conductive filler is relatively costly, which causes an increase in manufacturing cost of heat dissipating substrates manufactured by using the same. Particularly, when the content of the heat-conductive filler is raised to 70 wt % or more in order to increase the heat dissipation efficiency, the manufacturing unit cost may be increased and dispersion efficiency of the filler may be decreased, resulting in deteriorating manufacturing efficiency of the substrate. Moreover, carbon nano-materials, such as carbon nanotube, graphene, and carbon fiber, as an inorganic filler, have very high heat conductivity as compared with those used for the existing inorganic filler, but have difficulties in being applied as a filler of heat dissipating materials requesting both insulating property and excellent heat transfer property due to high electric conductivity of the carbon material itself.

RELATED ART DOCUMENT Patent Document

-   (Patent Document 1) Japanese Patent Laid-Open Publication No.     2010-238990

SUMMARY OF THE INVENTION

An object of the present invention is to provide a resin composition capable of improving heat dissipation efficiency of a heat dissipating substrate.

Another object of the present invention is to provide a heat dissipating substrate having improved heat dissipation efficiency.

According to an exemplary embodiment of the present invention, there is provided a resin composition for heat dissipation, including: an insulating material; a first filler added to the insulating material and having a plate shaped carbon material; and a second filler added to the insulating material, and having a carbon material having a higher aspect ratio than the first filler.

The first filler may include graphene or graphene oxide, and wherein the second filler includes carbon nanotube.

Here, a total content of the first filler and the second filler may be below 3 wt % based on the resin composition for heat dissipation.

The insulating material may include a polymer epoxy resin.

The first filler and the second filler each may be surface-coated with an inorganic material.

The inorganic material may include at least any one of silica, titanium oxide (TiO₂), aluminum oxide (Al₂O₃), boron nitride (BN), and zinc oxide (ZnO).

According to another exemplary embodiment of the present invention, there is provided a heat dissipating substrate manufactured by using a resin composition for heat dissipation, the resin composition having an insulating material; a first filler having a plate shaped carbon material; and a second filler having a carbon material having a higher aspect ratio than the first filler.

The first filler may form a primary heat-conductive network in the insulating material, and the second filler may form a secondary heat-conductive network by being inserted into the first filler in the insulating material.

The first filler may include graphene or graphene oxide, surface-coated with an inorganic material, and the second filler may include carbon nanotube surface-coated with an inorganic material.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a resin composition for heat dissipation according to an exemplary embodiment of the present invention;

FIG. 2 is a view showing a package structure having a heat dissipating substrate according to the exemplary embodiment of the present invention; and

FIG. 3 is a view showing a detailed structure of the heat dissipating substrate shown in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Various advantages and features of the present invention and methods accomplishing thereof will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings. However, the present invention may be modified in many different forms and it should not be limited to the exemplary embodiments set forth herein. Rather, these exemplary embodiments may be provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Identical reference numerals denote identical elements, throughout the description.

Terms used in the present specification are for explaining the exemplary embodiments rather than limiting the present invention. In the specification, a singular type may also be used as a plural type unless stated specifically. The word “comprise” and variations such as “comprises” or “comprising,” will be understood to imply the inclusion of stated constituents, steps, operations and/or elements but not the exclusion of any other constituents, steps, operations and/or elements.

Further, the exemplary embodiments described in the specification will be described with reference to cross-sectional views and/or plan views that are ideal exemplification figures. In the drawings, the thickness of layers and regions is exaggerated for efficient description of technical contents. Therefore, exemplified forms may be changed by manufacturing technologies and/or tolerance. Therefore, the exemplary embodiments of the present invention are not limited to specific forms but may include the change in forms generated according to the manufacturing processes. For example, an etching region vertically shown may be rounded or may have a predetermined curvature.

Hereinafter, a resin composition for heat dissipation and a heat dissipating substrate manufactured by using the same according to the exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a diagram showing a resin composition for heat dissipation according to a preferred embodiment of the present invention. Referring to FIG. 1, a resin composition for heat dissipation 100 according to a preferred embodiment of the present invention may include an insulating material 110, a first filler 120, and a second filler 130.

As the insulating material 110, various kinds of resins may be used. As the insulating material 110, a polymer epoxy resin may be used. The polymer epoxy resin may be used as an insulating material of a heat dissipating substrate when a build-up multilayer circuit board is manufactured. For this reason, it is preferable to use a polymer epoxy resin having excellent heat resistance, chemical resistance and electrical characteristics. For example, as the insulating material 110, a polymer epoxy resin may be used. More specifically, as the epoxy resin, at least any one heterocyclic epoxy resin of bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, dicyclopentadiene type epoxy resin, and triglycidyl isocyanate may be used. Alternatively, as the epoxy resin, a bromine-substituted epoxy resin may be used.

As the first filler 120, a plate shaped carbon nano-material having a large area as compared with the second filler 130 may be used. For example, as the first filler 120, graphene or graphene oxide may be used. The graphene generally has a thin film shape, and thus has a relatively low aspect ratio, and may have relatively higher electric conductivity and heat conductivity than inorganic fillers such as silica, titanium dioxide, aluminum dioxide, and the like. The first filler 120 is provided in an oxide type, and thus, may be preferably applicable to an insulating material due to low electric conductivity thereof.

As the second filler 130, a carbon nano-material having a relatively high aspect ratio as compared with the first filler 120 may be used. For example, as the second filler 130, a carbon nanotube may be used. The carbon nanotube has a generally long and slim shape, and thus a high aspect ratio, and may have relatively higher electric conductivity and heat conductivity than the inorganic filler.

Meanwhile, the first and second fillers 120 and 130 each may be coated with an insulating material such as an inorganic material. That is, an inorganic coating film 122 may be formed on a surface of the first filler 120 and an inorganic coating film 132 may be formed on a surface of the second filler 130. The insulating material may be used to coat the first and second fillers 120 and 130, in order to apply a carbon nano-material having relatively high electric conductivity to a heat dissipating material having insulating property. As the insulating material, silica, boron nitride (BN), or metal oxide may be used. As the metal oxide, at least one of titanium dioxide (TiO₂), aluminum oxide (Al₂O₂), and zinc oxide (ZnO) may be used.

As described above, the resin composition for heat dissipation 100 according to the exemplary embodiment of the present invention may be composed of the insulating material 110, the first filler 120, i.e., a plate shaped carbon nano-material such as graphene, and a second filler 130, i.e., a carbon nanotube having a high aspect ratio. In this case, the first filler 120 occupying a relatively large area forms a primary heat-conductive network within the resin composition for heat dissipation 100, and the second filler 130 is inserted between the graphene oxides to form a secondary heat-conductive network, thereby increasing the mean free movement path. Accordingly, the resin composition for heat dissipation and the heat dissipating substrate manufactured by using the same according to the present invention can exhibit high heat conductivity characteristics, by adding graphene and carbon nanotube together as a filler to the insulating material so that the graphene having a relatively larger area forms a primary heat-conductive network and the carbon nanotube having a high aspect ratio forms a secondary heat-conductive network in the network formed by the graphene.

In addition, the resin composition for heat dissipation and the heat dissipating substrate manufactured by using the same according to the present invention provide graphene and carbon nanotube to form multiple heat-conductive networks, and thus, can exhibit high heat conductivity characteristics even with relatively low contents of graphene and carbon nanotube, as compared with a case where only any one of the graphene and carbon nanotube is used to form a single heat-conductive network.

In succession, a heat dissipating substrate and a package structure manufactured by using the foregoing resin composition for heat dissipation 100 will be described in detail. The heat dissipating substrate and package structure explained herein are only examples for showing the technical spirits of the present invention, and thus the present invention is not limited thereto.

FIG. 2 is a view showing a package structure having a heat dissipating substrate according to the preferred embodiment of the present invention; and FIG. 3 is a view showing a detailed structure of the heat dissipating substrate shown in FIG. 2.

Referring to FIGS. 2 and 3, a package structure 200 according to the preferred embodiment of the present invention may include a heat dissipating substrate 210, a chip component 220 provided on the heat dissipating substrate 210, and a molding film 230 covering the chip component 220.

The heat dissipating substrate 210 may be manufactured by using the resin composition for heat dissipation 100 set forth above as an insulating material. The heat dissipating substrate 210 may be composed of a core layer 212 and a buildup film 214 covering the core layer 212. The heat dissipating substrate 210 may have a circuit pattern 216 electrically connected with the chip component 220. The chip component 220 may belong to various kinds of electronic components, and the molding film 230 may cover the chip component 220 to protect the chip component 220 from the external environment.

The above heat dissipating substrate 200 may be manufactured by using the resin composition for heat dissipation 100 set forth above. First, an insulating material 110 and first and second fillers 120 and 130 may be mixed in a predetermined solvent, to prepare a mixture. Here, in the procedure of preparing the mixture, various kinds of hardener and hardening accelerator, and other various additives may be further added.

As the insulating material 110, an epoxy resin may be used. Examples of the epoxy resin may include at least any one heterocyclic epoxy resin of bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, dicyclopentadiene type epoxy resin, and triglycidyl isocyanate. Alternatively, as the epoxy resin, at least one of bromine substituted epoxy resins may be used.

As the hardener, at least any one of amines, imidazoles, guanines, acid anhydrides, dicyandiamides, and polyamines may be used. Alternatively, as the hardener, at least any one of 2-methyl imidazole, 2-phenyl imidazole, 2-phenyl-4-phenyl imidazole, bis(2-ethyl-4-methyl imidazole), 2-phenyl-4-methyl-5-hydroxymethyl imidazole, triazine additive type imidazole, 2-phenyl-4,5-dihydroxymethyl imidazole, phthalic anhydride, tetrahydrophthalic anhydride, methylbutenyl tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhydro phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, and benzophenonetetracarboxylic anhydride may be used.

As the hardening accelerator, at least any one of phenols, cyanate esters, amines, and imidazoles may be used.

The additives may be provided in order to improve manufacturing characteristics and substrate characteristics in the case where an insulating film is manufactured by using the polymer resin composition and further in the case where a multilayer circuit board is manufactured by using the insulating film. For example, the additives may include an auxiliary filler, a reactive diluent, a binder, and the like.

As the auxiliary filler, an inorganic or organic filler may be used. For example, as the auxiliary filler, at least any one of barium sulfate, barium titanate, silicon oxide powder, amorphous silica, talc, clay, and mica powder may be used.

The reactive diluent may be material for controlling viscosity at the time of preparing the polymer resin composition to thereby smooth manufacture workability. The reactive diluent may include at least any one of phenyl glycidyl ether, resorcin diglycidyl ether, ethylene glycol diglycidyl ether, glycerol triglycidyl ether, resol type novolac type phenolic resins, and isocyanate compounds.

The binder may be provided in order to improve flexibility of the insulating film manufactured by using the polymer resin composition and also improve material characteristics. The binder may include at least any one of polyacryl resin, polyamide resin, polyamideimide resin, polycyanate resin, and polyester resin.

Also, the polymer resin composition may further include a predetermined rubber as the additive. For example, an insulating film laminated on an inner layer circuit is subjected to a wet conditioning process using an oxidizing agent in order to improve adhesive strength with a plating layer after pre-hardening. Accordingly, rubber soluble in the oxidizing agent or epoxy modified rubber resin may be used in an insulating film composition as a conditioning component (rubber). Examples of the rubber used may include, but are not particularly limited to, at least one of poly butadiene rubber, epoxy-modified, acrylonitrile-modified, and urethane-modified poly butadiene rubbers, acrylonitrile butadiene rubber, and acrylic rubber dispersed epoxy resins.

Graphene oxide coated with silica may be used as the first filler 120, and carbon nanotube may be used as the second filler 130. Both surfaces of the graphene oxide and the carbon nanotube may be coated with an inorganic material. Silica may be used as the inorganic material. The inorganic material may be prepared by using a sol-gel method of an inorganic material precursor, or may be directly prepared by dispersing inorganic particles and the carbon nano-material in the solvent and then using a chemical reducing method. Meanwhile, electric conductivity of the first and second fillers 120 and 130 each may be controlled by regulating the coating thickness of the inorganic material. The coating thickness of the inorganic material may be controlled by changing the weight ratio of the carbon nano-material and the inorganic material to 1:0.1 to 1:1.

The polymer composition for the heat dissipating substrate manufactured by the foregoing method is subjected to mixing and dispersing, and then casting, to be formed into a film. The mixing and dispersing of the polymer composition may be performed using a 3-ball mill roller. The insulating films manufactured by the foregoing method are laminated and fired, to form a build-up multilayer circuit board. In this process, metal circuit patterns may be formed on the insulating films, respectively. Therefore, the heat dissipating substrate 210 having a structure where at least one insulating film 214 is laminated on the core layer 212, and having the circuit pattern 216 electrically connected with the chip component 220 may be manufactured.

Hereinafter, specific examples of the resin composition for heat dissipation and the method for preparing the same according to the exemplary embodiment of the present invention set forth above will be described in detail.

Comparative Example 1

A carbon nanotube having a diameter of about 20 to 30 nm and a length of several μm was prepared as a heat-conductive filler, and then surface-treated with a chemical where sulfuric acid and nitric acid are mixed at a ratio of 3:1. This surface-treated carbon nanotube was surface-coated with silica. As a method for coating silica, a mixture where the carbon nanotube and silica were mixed at a ratio of approximately 1:0.5 was added to distilled water, and then dispersed by ultrasonification treatment for about 1 hour. After that, hydrazine as a reducing agent was added to the mixture liquid, and then stirred at 150 for 12 hours, inducing the reaction. This reacted material was washed and dried, to thereby prepare a carbon nanotube filler into which a silica layer is introduced. The prepared carbon nanotube filler was added to and dispersed in an epoxy resin composition, which was then hardened to prepare a polymer insulating material. The thus prepared polymer complex was made into a film, and heat dissipation characteristics thereof were measured.

Comparative Example 2

In Example 2 as compared with Comparative Example 1 set forth above, heat dissipation characteristics were measured while graphene oxide was replaced with carbon nanotube as a heat-conductive filler and other conditions are identical. The graphene oxide used herein had a structure made of ten graphite layers or less.

Example 1

As the heat-conductive filler, carbon nanotube and graphene oxide surface-coated with silica were used. Approximately 2 wt % of the graphene oxide coated with silica was added to an epoxy resin composition, and then stirred and dispersed for 1 hour. After that, approximately 0.25 wt % of the carbon nanotube was further added thereto and then stirred for 1 hour, so that the carbon nanotube was inserted into layers of the graphene oxide. The epoxy resin containing this graphene oxide and carbon nanotube was prepared into a polymer insulating material through a hardening reaction, and the thus prepared polymer complex was made into a film, and then heat dissipation characteristics thereof were measured.

Example 2

A polymer complex was prepared under the same conditions as Example 1 set forth above except that the carbon nanotube coated with silica was added in a content of 0.5 wt %. Then, the polymer complex was made into a film, and then heat dissipation characteristics thereof were measured.

Example 3

A polymer complex was prepared under the same conditions as Example 1 set forth above except that the carbon nanotube coated with silica was added in a content of 0.75 wt %. Then, the polymer complex was made into a film, and then heat dissipation characteristics thereof were measured.

Example 4

A polymer complex was prepared under the same conditions as Example 1 set forth above except that the carbon nanotube coated with silica was added in a content of 1.0 wt %. Then, the polymer complex was made into a film, and then heat dissipation characteristics thereof were measured.

Heat dissipation characteristics for samples of Comparative Examples 1 and 2 and Examples 1 to 4 manufactured as described above were tabulated in Table 1 below.

TABLE 1 Heat Dissipation Characteristics Insulating Graphene Carbon (Heat Conduc- Classification Material Oxide Nanotube tivity, W/mK) Comparative Epoxy Resin 2 wt % Not 0.265 Example 1 Comparative Epoxy Resin Not   1 wt % 0.246 Example 2 Example 1 Epoxy Resin 2 wt % 0.25 wt % 0.271 Example 2 Epoxy Resin 2 wt % 0.50 wt % 0.314 Example 3 Epoxy Resin 2 wt % 0.75 wt % 0.335 Example 4 Epoxy Resin 2 wt % 1.00 wt % 0.339

Referring to Table 1 above, Examples 1 to 4, where the polymer resin compositions using, as a filler, graphene oxide and carbon nanotube, which were coated with silica, was used as a resin composition for heat dissipation, exhibited higher heat dissipation efficiency than Comparative Example 1 using only graphene oxide as a filler and Comparative Example 2 using only carbon nanotube as a filler. Particularly, according to Examples 1 to 4, it was confirmed that mere addition of approximately 2 wt % of graphene oxide and addition of 0.25 wt % to 1.0 wt % of carbon nanotube resulted in exhibiting similar or superior heat dissipation effect as compared with the existing resin composition for heat dissipation where the inorganic filler was added in a content of 70 wt % or more and further 90 wt % or more. Therefore, when the graphene oxide and carbon nanotube coated with the silica were added in a total content of below approximately 3 wt %, significantly improved heat dissipation effect can be obtained as compared with the existing cases where the inorganic filler was used.

As set forth above, the resin composition for heat dissipation and the heat dissipating substrate manufactured by using the same according to the present invention can exhibit high heat conductivity characteristics, by adding graphene and carbon nanotube together as a filler to the insulating material so that the graphene having a relatively larger area forms a primary heat-conductive network and the carbon nanotube having a high aspect ratio forms a secondary heat-conductive network in the network formed by the graphene.

Further, the resin composition for heat dissipation and the heat dissipating substrate manufactured by using the same according to the present invention provide graphene and carbon nanotube to form multiple heat-conductive networks, and thus, can exhibit high heat conductivity characteristics even with relatively low contents of graphene and carbon nanotube, as compared with a case where only any one of the graphene and carbon nanotube is used to form a single heat-conductive network.

The present invention has been described in connection with what is presently considered to be practical exemplary embodiments. In addition, the above descriptions merely represent and explain the exemplary embodiments of the present invention, and the present invention may be changed or modified within the range of concept of the invention disclosed in the specification, the range equivalent to the disclosure and/or the range of the technology or knowledge in the field to which the present invention pertains. The exemplary embodiments described above have been provided to explain the best state in carrying out the present invention. Therefore, they may be carried out in other states known to the field to which the present invention pertains in using other inventions such as the present invention and also be modified in various forms required in specific application fields and usages of the invention. Therefore, it is to be understood that the invention is not limited to the disclosed embodiments. It is to be understood that other embodiments are also included within the spirit and scope of the appended claims. 

What is claimed is:
 1. A resin composition for heat dissipation, comprising: an insulating material; a first filler added to the insulating material and having a plate shaped carbon material; and a second filler added to the insulating material, and having a carbon material having a higher aspect ratio than the first filler.
 2. The resin composition for heat dissipation according to claim 1, wherein the first filler includes graphene or graphene oxide, and wherein the second filler includes carbon nanotube.
 3. The resin composition for heat dissipation according to claim 1, wherein a total content of the first filler and the second filler is below 3 wt % based on the resin composition for heat dissipation.
 4. The resin composition for heat dissipation according to claim 1, wherein the insulating material includes a polymer epoxy resin.
 5. The resin composition for heat dissipation according to claim 1, wherein the first filler and the second filler each are surface-coated with an inorganic material.
 6. The resin composition for heat dissipation according to claim 5, wherein the inorganic material includes at least any one of silica, titanium oxide (TiO₂), aluminum oxide (Al₂O₃), boron nitride (BN), and zinc oxide (ZnO).
 7. A heat dissipating substrate manufactured by using a resin composition for heat dissipation, the resin composition having an insulating material; a first filler having a plate shaped carbon material; and a second filler having a carbon material having a higher aspect ratio than the first filler.
 8. The heat dissipating substrate according to claim 7, wherein the first filler forms a primary heat-conductive network in the insulating material, and wherein the second filler forms a secondary heat-conductive network by being inserted into the first filler in the insulating material.
 9. The heat dissipating substrate according to claim 7, wherein the first filler includes graphene or graphene oxide, surface-coated with an inorganic material, and wherein the second filler includes carbon nanotube surface-coated with an inorganic material. 